CONCEPT
The API Mandate
Amazon's decree that all teams expose functionality through defined interfaces only—no shared databases, no back-channels—engineering communication to shape architecture.
Amazon's early-2000s organizational policy requiring that all inter-team interaction occur through application programming interfaces (APIs). Teams could not share databases, could not make back-channel agreements, could not communicate about system behavior except through the documented interfaces their services exposed. The mandate was radical because it constrained not just technical implementation but organizational communication itself—the social channels through which teams could coordinate were deliberately narrowed. This was the Inverse Conway Maneuver made policy: if systems copy communication structures, then engineer the communication structure to produce the architecture you want. The mandate produced Amazon's service-oriented architecture not by teaching teams to build services but by forcing them to communicate only through service boundaries.
In The You On AI Field Guide
The mandate's genius was treating communication channels as architectural decisions. In most organizations, communication happens through whatever channels prove convenient—shared databases because they're fast, informal hallway conversations because they're easy, back-channels because formal processes are slow. Each convenience introduces coupling that becomes architectural debt. Amazon recognized that the convenience was the problem: easy communication between teams